﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Chapter_8
{
    class Program
    {
        static void Main(string[] args)
        {
            string a = "abcabcabc";
            string b = a.Replace("b", "bb");
            Console.WriteLine(b);
            
        }
    }
}
